Certain airborne radars comprise imaging modes making it possible to represent a zone or an object in a certain frequency band.
In particular, the SAR (Synthetic Aperture Radar) imaging mode makes it possible to carry out a picture capture of a ground zone or of a boat and the ISAR (Inverse Synthetic Aperture Radar) imaging mode allows picture capture of the superstructure of a ship.
In both these modes, the quality of the image obtained is highly dependent, inter alia, on the relative disposition of the carrier of the radar with respect to the target and on the speed of the target. For example, for optimal picture capture in SAR mode, the target must be situated in a certain direction with respect to the carrier during picture capture.
In a general manner, to get an SAR image the boat must not move (little or no swell) whilst in ISAR it must move (swell necessary).
In the absence of suitable assistance, compliance with these positioning constraints requires close attention on the part of the pilot of the carrier as well as solid experience in carrying out these operations.
At present, embedded mission systems provide the pilot at best with prompts based on the current position of the carrier and of the direction of the target. The pilot is therefore furnished with indications of the domain in which an image capture is possible.
This operative mode exhibits several drawbacks.
Firstly, it does not make it possible to anticipate the entire picture capture procedure. Secondly, it does not guarantee an optimal result in terms of image quality, given that these prompts can only be approximate.
Finally, this operative mode relies on the pilot's experience and attention.
Another drawback resides also in the fact that, the picture capture conditions varying, the images obtained cannot easily be used subsequently to feed an automatic target recognition system.